Đáp án:
$\begin{array}{l}
c)\int {f\left( x \right)dx} \\
= \int {\left( {{x^2} + co{s^2}\frac{x}{2}} \right)dx} \\
= \int {\left( {{x^2} + \frac{{{\rm{cosx + 1}}}}{2}} \right)dx} \\
= \frac{{{x^3}}}{3} + \frac{1}{2}\sin x + \frac{1}{2}x + C\\
d)\int {f\left( x \right)dx} \\
= \int {\left( {2x + {{\sin }^2}\frac{x}{2}} \right)dx} \\
= {x^2} + \int {\frac{{1 - \cos x}}{2}dx} \\
= {x^2} + \frac{1}{2}x - \frac{1}{2}\sin x + C
\end{array}$
